Piston means for gas-operated firearms



y 1945. D. M. WILLIAMS 3 15 PISTON-MEANS FOR GAS-OPERATED FIREARMS Filed April 25, 1943 2 Sheets-Sheet l 1945- D. M. WILLIAMS PISTON-MEANS FOR GAS-OPERATED FIREARMS Filed April 25. 1943 2 Sheets-Sh et 2 r4i ormegs Patented May 22, 1945 TENT OFFEE EISTON MEANS FOR GAS-OPERATED FIREARMS ware Application April 23, 1943, Serial No. 484,175

10 Claims.

The present invention relates to improvements in gas-operated self-loading firearms and relates more particularly to improvements in pistonmeans for gas-operated firearms of the type wherein the stroke of the piston under the urge of gases from the bore of the barrel of the firearm is but a fraction of the stroke of the breechbolt or its equivalent which the piston serves to actuate.

In gas-operated firearms of the type above referred to, the power-stroke of the piston is checked by abutment-means and the present invention relates to a construction and arrangement of parts whereby the piston may have its stroke normally limited but may be at will readily released for dismounting.

One of the objects of the present invention is to provide superior piston-means for gas-operated self-loading firearms in which the parts are so constructed and arranged as to effectively limit the power-stroke of the piston during the normal operation of the firearm but with provision for the ready release of the piston for dismounting from the firearm-structure,

Another object of the present invention is to provide superior piston-means for gas-operated self-loading firearms wherein the parts are so constructed and arranged as to provide for the effective limiting of the power-strok of the piston without damage to the structure over long periods of use.

With the above and other objects in View, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art and which are not claimed in any separate application.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a broken view in side elevation of a firearm-barrel equipped with the improved piston-means of the present invention, the piston proper being shown in its normal forward position;

Fig. 2 is an underside view thereof;

Fig. 3 is a broken view partly in side elevation and partly in vertical central-longitudinal section of the barrel and piston-means and with the piston proper shown in its rearward position;

Fig. 4 is a transverse sectional view taken on the line 4 i of Fig. 1;

Fig. 5 is a similar View taken on the line 55 of Fig. 1;

Fig. 6 is a view similar to Fig. l but showing the same mainly from the rear and underside;

Fig. 9 is a perspective view of the piston, detached;

I Fig. 10 is a similar view of the retaining-plate, detached;

Fig. 11 is a View similar to but less comprehensive than Fig. 3 and showing an alternative form of retaining-means for the piston; and

Fig. 12 is aperspective view of the piston shown in Fig. 11, viewing the same mainly from the rear.

The structure of Figs. 1 to 10 inclusive The particular firearm-structur herein chosen for purposes of illustrating one form of the present invention, includes a barrel i5 suitable for use as a component of a gas-operated self-loading firearm and having a usual axial bore l6 extending therethrough for the passage of projectiles in the usual manner of firearms. Intermediate its respective opposite ends the barrel I5 is formed with a rigid depending cylinder-lug ll.

Also depending from the barrel I5 is a rigid stop-lug I8 which is preferably formed integral with the said barrel, as is also the aforesaid cylinder-lug IT. The stop-lug I8 is located rearwardly with respect to the cylinder-lug l! and is separated therefrom by an transverse downwardlyopening notch-like gap I9.

The cylinder-lug I! before referred to is formed with 'a cylindrically-contoured rearwardly-opening piston-chamber 2t having a relatively-heavy front Wall 2|. Leading forwardly and upwardly from the forward portion of the piston-chamber 20 in the said cylinder-lug I1 is an inclined gaspassage 22 which communicates at its upper end with the bore l6 of the barrel l5 and intersects the rear face of the front wall 2! of the cylinder-lug ll at a point slightly below the upper end of the piston-chamber 20.

In its under face, midway between its respective opposite sides, the stop-lug I8 is .formed with a downwardly-opening cylindrically-contoured clearance-notch 23 arranged coaxially with respect to the piston-chamber 20 before referred to. The lower face of the stop-lug H! of the barrel I5 lies in a horizontal plane which is very slightly above a horizontal plane intersecting the centrallongitudinal axis of the piston-chamber 26 in the cylinder-lug H.

In each of its respective opposite sides, the cylinder-lug I! is formed with one of two longitudinal retaining-grooves 24-24, as is shown especially well in Fig. 8. The upper wall of each of the said retaining-grooves 24-24 is in substantially the same horizontal plane as that occupied by the under face of the stop-lug I 8, for purposes as will hereinafter appear.

Reciprocating in the piston-chamber 26 of the cylinder-lug I1 is the cylindrically-contoured head 25 of a piston generally designated by the reference character 26. In addition to its head 25, the said piston 25 includes a rearwardly-projecting cylindrically-contoured stem 21 which reciprocates in the clearance-notch 23 of the stoplug 18. The features 23 and 21 are preferably so proportioned that the latter rides free of the former during the operation of the piston, though if desired they may have a bearing-interengagement. Intermediate its respective opposite ends,

the piston 28 is formed with a, rigid and preferably a integral stop-flange 28 which is but very slightly less than a semi-circle in extent and which has its terminal faces extending substantially diametrically with respect to the piston and constituting what may be aptly designated as guide-faces lug 18, as is shown especially well in Figs. 1, '2 and 3. For purposes of maintaining the piston 26 in position to locate its stop-flange 23 in the gap IS, a retaining-plate 29 maybe employed.

The retaining-plate 29 above referred to may be conveniently formed of spring-tempered sheet steel and includes two rearwardly-extending laterally-spaced-apart arms 30"30 respectively fitting'into the retaining-grooves 24-24 in the respective opposite sides of the cylinder-lug ll. Each of the arms 30-38 is widened inwardly at its rear end toward the complemental arm to provide one of two plate-like guide-fingers 3 I-3l respectively underlying the radially-arranged guide-faces nae-28a of the stop-flange 28. Extending centrally forwardly from the retaining-plate 29 is a slender tail 32 preferably sized to fit the inclined gas-passage 22 in the barrel i and its cylinder- -lug I! when it is desired to clean the said pas-- sage. Normally, the tail 32 extends closely adjacent the under face of that portion of the barrel l5 lying forwardly of the cylinder-lug H.

The piston 26 may actuate a wide variety of mechanisms such, for instance, as an action-slide 33 indicated by broken lines in Fig. 1. The said action-slide per se forms no essential feature of the present invention but is in the instance shown yieldingly pressed forwardly by a helical spring 34 also represented by broken lines in Fig. 1.

Normally, the piston 26 is at the limit of its forward movement, as is shown particularly well in Figs. 1 and 2, in which position the forward face of the head of'the said piston 26 is held in engagement with the rear face of the front wall 2| of the cylinder-lug ll-by the spring 34.

Operation 'Let it be assumed for purposes of description that the firearm is loaded in readiness for'being discharged. The discharge of the firearm will cause a bullet to be forced forwardly through the ton 26 will be positively checked by the engagemerit of the rear face of its stop-flange 28 with the forward face of the stoplug l8 depending from the .barrel iii.

The very rapid though relatively-short rearward travel of the piston 26 as above described, will impart to the action-slide 33 or other desired feature of the firearm a similar rearward movement which latter movement, however, will continue after the said piston has had its rearward movement checked'by the engagement of its stop-flange 23 with the stop-lug I8. When the energy developed by the discharge of the firearm and the energy stored in the action-slide 33 have dissipated themselves, the said action-slide will return to its forward position under the urge of the spring 34 and will again move the piston 28 into its forward position, as is especially well shown in Figs. 1 and 2.

During its axial movement, the piston 26 will be held against turning movement with respect to the barrel l5 and associated parts by the coaction of the respective upper faces of the guidefingers -3! of the retaining-plate 29 with the guide-faces 28a--23a of the stop-flange 28 of the said piston.

.Dismounting the piston When it is desired for any reason to dismount the piston 26 or its equivalent from the firearmstructure, the retaining-plate 29 should first be removed. The removal of the retaining-plate 29 may be effected by outwardly springing its arms 30-38 and sliding the entire guide-plate for- Wardly until the rear or outer ends of the guidefingers 3I--3| have cleared the forward ends of the retaining-grooves 2424 in the cylinder-lug The piston 25 may now be turned about its longitudinal axis through an arc of substantially 180 so that its substantially-semicircular stop-flange 28' is completely cleared from the gap [9, and thereby placed entirely below the stop-lug [8. Under these conditions, the radial guide-faces file-28a of the stop-flange 23 will face upwardly, as indicated in Figs. 6 and 7, whereupon the entire piston 26 may be moved rearwardly until the head 25 of the said piston is completely free of the rear end of the piston-chamber 22. The piston will now be entirely free for removal from the firearm-structure.

To reassemble the piston with the firearmstructure, the operations above described in connection with its removal may be reversed.

The structure of Figs. 11 and 12 said piston is turned into full registry with the gap l9 between the cylinder-lug H and the stoplug l8.

The detent above referred to is in the form of a hard steel ball or its equivalent and is located in the contracted lower end of a vertical pocket 31 located centrally in the stop-lug I8 and intersecting the clearance-notch 23 therein. The detent 35 is pressed downwardly with capacity for upward yielding movement, by means of a helical spring 38 mounted in the upper portion of the pocket 31.

When it is desired to dismount the piston 39 of the structure of Fig. '7, the said piston may be forcibly rotated about its central-longitudinal axis to thereby upwardly retire the detent 35. When the piston 26 now being described has been turned a full half-turn, it will have the guidefaces 23a28a of its stop-flange 28 located entirely below the stop-lug id of the barrel is and will thereby be free for rearward movement to a degree sufficient to completely remove its head 25 from the piston-chamber 23 in the cylinderlug i'l, in a manner corresponding to that described in connection with the structure of Figs. 1 to 10 inclusive.

The invention may be carried out in other specific ways than those herein set forth with out departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all change coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel'and provided with a piston-chamber open at one end and also provided with a gas-passage connecting the said piston-chamber with the bore of the said barrel; a first stop-abutment located adjacent the said cylinder and facing in opposition to the open end of the piston-chamber therein; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder, the said piston being provided with a stop-abutment facing in opposition to and normally engageable with the aforesaid first stopabutment when the piston is moved by gas pressure in the piston-chamber of the said cylinder; the said stop-abutments being constructed and arranged so that the stop-abutment of the said iston may be moved out of registry with the said first stop-abutment by a transverse turning movement of the said piston to thereby relieve the said piston of restraint by the said first stop-abutment; and retaining-means constructed and arranged to releasably hold the said piston in a, transverse position wherein its said stop-abutment will engage with the said first stop-abut ment to thereby limit the stroke of the said piston when the firearm is discharged.

2. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber open at one end and also provided with a gaspassage connecting the said piston-chamber with the bore of the said barrel; a first stop-abutment located adjacent to and facing toward the open end of the pistonchamber in the said cylinder; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder, the said piston being provided with a stop-abutment facing in oposition to and normally engageable with the aforesaid first stopabutment when the piston is moved by gas pressure in the piston-chamber of the said cylinder; the said stop-abutments being constructed and arranged so that the stop-abutment of the said piston may be moved out of registry with the said first stop-abutment by a transverse turning movement of the said piston to thereby relieve the said piston of restraint by the said first stopabutment; and retaining-means constructed and arranged to releasably hold the said piston in a transverse position wherein its said stop-abutment will engage with the said first stop-abutment to thereby limit the stroke of the said piston when the firearm is discharged.

3. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided. with a rearwardly-opening pistonchamber and with a gas-passage connecting a forward portion of the said piston-chamber with the bore of the said barrel; a forwardly-facing stop-abutrnent located adjacent the said cylinder; a piston constructed and arranged to both re ciprocate and transversely turn in the rearwardly-opening piston-chamber of the said cylinder, the said piston being provided with a rearwardly-iacing stop-abutment normally engage able with the aforesaid forwardly-facing stop abutment when the piston is moved rearwardly by gas pressure in the piston-chamber of the said cylinder; the said stop-abutments being constructed and arranged so that the rearwardlyfacing stop-abutment of the said piston may be turned out of registry with the said forwardlyfacing stt p-abutment by a transverse turning movement of the said piston to thereby permit the stop-abutment of the said piston to move rearwardly past the said forwardly-facing stopabutment; and retaining-means constructed and arranged to releasably hold the said piston in a tansverse position wherein its rearwardly-facing stop-abutment will engage with the said forwardly-facing stop-abutment to thereby limit the stroke of the said piston when the firearm is discharged.

4.. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a rearwardly-opening pistonchamber and with a gas-passage connecting a forward portion of the said piston-chamber with the bore of the said barrel; a forwardly-facing stop-abutment spaced rearwardly from the open end of the piston-chamber in the said cylinder; a piston constructed and arranged to both reciprocate and transversely turnin the pistoncham-ber of the said cylinder, the said piston being provided with a rearwardly-facing stop-abutment normally engageable with the aforesaid forweirdly-facing stop-abutment when the piston is moved rearwardly by gas pressure in the pistonchamber of the said cylinder; the said stop-abutments being constructed and arranged so that the rearwardly-facing stop-abutment of the said piston may be turned out of registry with the said forwardly-facing stop-abutment by a transverse turning movement of the said piston to thereby permit the stop-abutment of the said piston to move rearwardly past the said forwardly-facing stop-abutment; and retaining-means constructed and arranged to releasably hold the said piston in a transverse position wherein its said stopabutment will engage with the said iforwardlyfacing stop-abutment to thereby limit the stroke of the said piston when the firearm is discharged.

5. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber open at one end and also provided with a gas-passage connecting the said piston-chamber with the bore of the said barrel; a stop-abutment carried by the said barrel and facing in opposition to the open end of the piston-chamber of the said cylinder; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder, the said piston being provided with a stop-abutment facing in opposition to and normally engageable with the stop-abutment of the said barrel when the piston is moved by gas pressure in the piston-chamber of the said cylinder; the said stop-abutments being constructed and arranged so that the stop-abutment of the said piston may be moved out of registry with the stop-abutment of the said barrel by a transverse turning movement of the said piston to thereby relieve the said piston of restraint by the stopabutment of the barrel; and retaining-means constructed and arranged to releasably hold the said piston in a transverse position wherein its said stop-abutment will engage with the stopabutment of the said barrel to thereby limit the stroke of the said piston when the firearm is discharged.

6. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a rearwardly-opening pistonchamber and with a gas-passage connecting a forward portion of the said piston-chamber with the bore of the said barrel; a forwardly-facing stop-abutment carried by the said barrel and spaced rearwardly from and facing toward the open rear end of the piston-chamber of the said cylinder; a piston constructed and arranged to both reciprocate and transversely turn' in the piston-chamber of said cylinder, the said piston being provided with a rearwardly-facing stop-abutment normally engageable with the forwardly-facing stop-abutment of the said barrel when the piston is moved by gas pressure in the piston-chamber of the said cylinder; the said stop-abutments being constructed and arranged so that the rearwardly-facing stop-abutment of the said piston may be moved out of registry with the forwardlyfacing stop-abutment of the said barrel by a transverse turning movement of the said piston; and retaining-means constructed and arranged to releasably hold the said piston in a transverse position wherein its rearwardly-facing stopabutment will normally engage with the forwardly-facing stop-abutment of the said barrel to thereby limit the stroke of the said piston when the firearm is discharged.

7. A firearm-structure including in com-bination: a barrel having an axial bore therethrough; a cylinder-lug rigid with and laterally ofisett-ing from the said barrel, the said cylinder-lug being formed with a piston-chamber having an open end and also formed with a gas-passage connecting an inner portion of the said piston-chamber with the bore of the said barrel; a stop-abutment carried by the said barrel and spaced from and facing toward the open end of the pistonchamber in the said cylinder-lug; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder-lug, the said piston being provided with a stop-abutment normally engageable with the stop-abutment carried by the said barrel when the piston is advanced by gas pressure in the piston-chamber of the said cylinder-lug; the said stop-abutments being constructed and arranged so that the stop-abutment of the said piston may be moved out of registry with the stop-abutment of the said barrel by a transverse turning movement of the said piston; and retaining-means constructed and arranged to releasably hold the said piston in a transverse position wherein its said stop-abutment will engage with the stop-abutment of the said barrel to thereby limit the stroke of the said piston when the firearm is discharged.

8. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder-lug rigid with and laterally-offsetting from the said barrel, the said cylinder-lug being formed with a rearwardly-opening piston-cham ber and with a gas-passage connecting a forward portion of the said piston-chamber with the bore of the said barrel; a stop-abutment carried by the said barrel and rearwardly spaced from and facing forwardly toward the open end of the piston-chamber in the said cylinder-lug; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder-lug, the said piston being provided with a rearwardly-facing stop-abutment normally engageable with the aforesaid forwardlyfacing stop-abutment carried by the said barrel when the piston is'moved rearwardly by gas pressure in the piston-chamber of the said cylinderlug; the said stop-abutments being constructed and arranged so that the rearwardly-facing stopabutment of the said piston may be moved out of registry with. the forwardly-facing stop-abutment of the said barrel by a transverse turning movement of the said piston; and retainingmeans constructed and arranged to releasably hold the said piston in a transverse position wherein its said rearwardly-facing stop-abutment will engage with the said forwardly-facing stop-abutment of the barrel to thereby limit the rearward stroke of the said piston when the firearm is discharged.

9. A firearm-structure including in combina tion: a barrel having an axial bore therethrough: a cylinder-lug rigid with and laterally ofisetting from the said barrel, the said cy1inder-lug being formed with a piston-chamber extending longitudinally of-the said barrel and having an open end, the said cylinder-lug also being formed with a gas-passage connecting an inner portion of the said piston-chamber with the bore of the said barrel; a stop-lug rigid with and laterally offsetting from the said barrel in spaced relationship with respect to the open end of the piston-chain ber in the said cylinder-lug and having a stopface facing toward the open end of the pistonchamber in the said cylinder-lug, the said stoplug being formed with a notch longitudinally in line with the longitudinal axis of the pistonchamber in the said cylinder-lug; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder-lug and in the notch of the said stop-lug, the said piston being provided with a rearwardly-facing stop-abutment normally engageable with the stop-face of the said stop-lug when the piston is advanced by gas pressure in the piston-chamber. of the said cylinder-lug; the stop-abutment of the said piston and the stopface of the said stop-lug being constructed and arranged so that the said stop-abutment may be moved out of registry with the stop-face of the said stop-lug when the said piston is transversely turned; and retaining-means constructed and arranged to releasably hold the said piston in a transverse position wherein its said stopabutment will engage with the stop-face of the said stop-lug to thereby limit the advance stroke of the said piston when the firearm is discharged.

10. A firearmtructure including in combination: a barrel having an axial bore therethrough;'

a cylinder-lug rigid with and laterally ofisetting from the said barrel and formed with a rearwardly-opening piston-chamber extending in substantial parallelism with the bore of the said barrel, the said cylinder-lug also being formed with a gas-passage connecting aforward portion of the said piston-chamber therein with the bore of the said barrel; a stop-lug rigid with and laterally ofisetting from the said barrel at a point rearwardly with respect to the said cylinder-lug and having a front stop-face extending substantially perpendicularly with respect to the bore of the said barrel, the said stop-lug being formed in its outer face with a notch extending longitudinally in line with the longitudinal axis of the piston-chamber in the said cylinder-lug; a piston constructed and arranged to both reciprocate and transversely turn in the piston-chamber of the said cylinder-lug and in the notch of the said stop-lug, the said piston being provided with a laterally-projecting stop-flange having a rear stop-face normally engageable with the front stop-face of the said stop-lug; the said stop-lug and the stop-fiange of the said piston being constructed, arranged and proportioned so that the stop-flange of the said piston may be moved out of registry with the said stop-lug by a turning movement of the said piston about its longitudinal axis; and retaining-means constructed and arranged to releasably hold the said piston in position wherein its said stop-flange will engage with the said stop-lug to thereby limit the rearward stroke of the said piston when the firearm is discharged.

DAVID M. WILLIAMS. 

